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GCSE Combined Science · key term
A formula showing the simplest whole-number ratio of the elements in a compound.
Used by AQA and Edexcel
Specification 5.2.1.3 · Paper 3
Revise: Structure of Ionic CompoundsAn empirical formula gives the simplest whole-number ratio of the elements in a compound. For an ionic compound, it describes the ratio of ions throughout the structure; it does not describe a separate molecule.
Specification Calculations involving masses · Paper 3, Paper 4
A formula showing the simplest whole-number ratio of atoms of each element in a compound.
Revise: Determining empirical and molecular formulaeAn empirical formula gives the simplest whole-number ratio of atoms of each element in a compound. For example, MgO means that magnesium and oxygen atoms are present in a ratio of 1:1. A subscript of 1 is not written.
For an empirical formula, use a representative ratio and simplify it. A cropped edge or single layer may not contain the same ratio as the whole lattice.
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